Acknowledge, Apologize, and Act!
You WILL fuck up. You WILL make mistakes. You WILL hurt the feelings of the person/people you love. What you choose to do with it at that point is often the difference between happy, healthy, growing relationship dynamics, and ones where people are shoving things down each others throats until someone explodes in a shower of death and destruction.
So, let's say you've just missed your mark. You said you'd do X, and it didn't happen. Moreover, that impacted at least one other person in your network. What then? Sometimes, if it's a biggie, or there is extra emotional energy around that error, it can seem pretty attractive to gloss over it, and just try to move forward. Just employ the whole, "Here's some flowers! Aren't they pretty? Love you!" approach that has been immortalized in popular culture. At that point, the injured party is just supposed to forgive and forget, and get on with things. No dog house, no conversation, and, most damaging in my estimation, no change. I'd recommend against that tactic.
Another option that I've seen is getting defensive about the whole thing. "Sure, I messed up, but it's not that big a deal, and you've also messed up before too, so get off my case! Geez....you're so sensitive..." If someone can't own responsibility for their own action (or inaction) I don't know that they're really ready for prime time.
Complete ignorance is another approach that is utilized to avoid confrontation and conflict following a mistake. If no one talks about it, doesn't overtly notice it at all, it didn't happen. This type of stuffing things to the back of the closet usually leads to explosive decompression of All The Things in a much more catastrophic fashion on down the road.
What to do? How does one fix an oops? Here's an approach that has worked well for me, both as the offender, and the offended:
The first step in any healing process is to acknowledge that an error was made. Whether it was under your control or not, something you did, or failed to do, negatively impacted someone you love. Say it out loud. Say it with empathy. "I know I said I would do X, but I'm not going to be able to hit that mark. I know X was important to you." If you can honestly add that it was important to you as well, do that.
If it's something that wasn't your fault, it's okay to say that, but don't allow it to be an excuse. "Traffic is really snarly. There's no way I'm going to be there on time for our date. I'm disappointed about that." is much better than just showing up 45 minutes behind with no acknowledgment.
"I'm sorry." So small a sentence. So fraught with peril and emotional baggage for many. Both from the giver and the receiver, there is vulnerability.
When I apologize, I'm owning up to a mistake, failure, omission, lack of ability or capacity, poor planning, or inability to predict my own emotional capacity. I kinda hate that. So I've practiced. I practice apologizing with small things that aren't so loaded, so that when the big ones come along, it's less clunky to get the words out, and my partners and I have had opportunities to feel that shared vulnerability together without the world being at risk.
When I am receiving an apology, it can be difficult to listen effectively, to hear what is being shared, without rushing into my own hurt feelings, frustrations, or past damage. It can be a challenge to stay open to forgiving someone, because it often feels safer to hold that hurt as a reminder to stay closed and protected, rather than being in a space of letting go, and moving forward together, particularly if there's an issue that is ongoing and repeated, rather than a one-off incident.
Now that you've acknowledged what happened, and shared an apology about it, it's time to take action! Apologies are just words unless there is change, progress, or an agreement on what happens next.
Is there a clear way to avoid repeating the error? Talk it out, agree upon that course of action, and implement it.
There are times where there isn't a fix in the moment, the opportunity has been missed, so the conversation is about what to do now that the previous plan is out the window? "I know that we missed the movie start time because I was running late. Let's find another activity together that would feel bonding, relaxing, and enjoyable this evening."
Complex issues usually resolve over time with incremental progress, rather than one grand planning session followed by perfect implementation. There may also be some backsliding at points. It can be easy to lose sight of forward momentum when an issue still is in development, circumstances are not ideal, or there is ambiguity about the path forward.
On the really deep things, I'd recommend trying to employ a more time lapse approach to viewing an incident. Chances are excellent that today is still a big step up from 6 months ago, for example, even if it went better last month. What small refinements can you see that would tip things further in the direction of good? Share those, and see if you can get buy in from your partners on making that happen!
Mistakes happen. That's life with imperfect people. Finding a path forward together in those moments are what spell success or failure in relationships. Acknowledge, Apologize, and find useful Action to move through it together. Screw ups are shared experiences that can build immense resilience and tensile strength in your relationships, if you're willing.